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<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
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<body>
    <script>
        function reverse(arr) {
            var newArr = []
            for (var i = arr.length-1; i >= 0 ;i--) {
                newArr[newArr.length] = arr[i]
            }
            return newArr
        }
        var res1 = reverse([12,23,2,34])
        console.log(res1);
    </script>
</body>
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